For long-distance optical fiber communication, it is desirable to provide a source of transform-limited optical pulses which is compact, reliable and stable, and which operates at an appropriate wavelength and repetition rate. In particular, it is currently believed that for soliton-based communication, a wavelength of about 1.55 .mu.m, a pulse width of 15-60 ps, and a repetition rate roughly in the range of 2.5-10 GHz are desirable. Actively mode-locked, semiconductor diode lasers are advantageously used as sources of optical pulses for such purposes. However, there are several problems associated with the conventional use of external air cavities for mode-locking. Such cavities generally require the use of bulk optics, a diffraction grating for wavelength control, and an etalon for bandwidth control. As a consequence, optical alignment is a complicated and difficult matter, and it is difficult to provide a cavity which is compact enough for general use in optical communication. As an alterative, monolithic mode-locked lasers have been proposed. Such lasers are described, for example, in P. A. Morton, et al., "Monolithic hybrid mode-locked 1.3 .mu.m semiconductor lasers," Appl. Phys. Lett. 56 ( 1990) 111-113. However, the small physical dimensions of such devices permit operation only at repetition rates which are relatively high, and generally greater than preferred maximum rates for purposes of data transmission. Moreover, some such devices lack adequate bandwidth control to produce relatively long pulses which are transform limited.